From 38b258bea2c6fc003ecb0e741b71c7b01fdeca77 Mon Sep 17 00:00:00 2001
From: tomsmeding <tom.smeding@gmail.com>
Date: Sun, 19 Jan 2020 20:59:42 +0100
Subject: Add option to remove v1 tags

---
 src/id3v1.rs | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 src/id3v1.rs

(limited to 'src/id3v1.rs')

diff --git a/src/id3v1.rs b/src/id3v1.rs
new file mode 100644
index 0000000..ccade4a
--- /dev/null
+++ b/src/id3v1.rs
@@ -0,0 +1,61 @@
+use std::fs::File;
+use std::io::{self, Read, Seek};
+
+#[derive(Copy, Clone, Debug)]
+pub enum TagType {
+    /// An ID3v1.0 tag
+    TAGv10,
+    /// An ID3v1.1 enhanced tag (TAG+) in addition to the v1.0 tag
+    TAGv11,
+    /// An ID3v1.2 extended tag (EXT) in addition to the v1.0 tag
+    TAGv12,
+}
+
+pub fn recognise(file: &mut File) -> io::Result<Option<TagType>> {
+    let length = file.seek(io::SeekFrom::End(0))?;
+    if length < 128 { return Ok(None); }
+
+    let mut buf4 = [0u8; 4];
+
+    // Check whether we have a v1.0 tag
+    file.seek(io::SeekFrom::End(-128))?;
+    file.read_exact(&mut buf4[0..3])?;
+    if &buf4[0..3] == b"TAG" {
+        // Check whether we also have a v1.1 tag
+        if length >= 128 + 227 {
+            file.seek(io::SeekFrom::End(-128 - 227))?;
+            file.read_exact(&mut buf4)?;
+            if &buf4 == b"TAG+" {
+                return Ok(Some(TagType::TAGv11));
+            }
+        }
+
+        // Otherwise, check whether we also have a v1.2 tag
+        if length >= 128 + 128 {
+            file.seek(io::SeekFrom::End(-128 - 128))?;
+            file.read_exact(&mut buf4[0..3])?;
+            if &buf4[0..3] == b"EXT" {
+                return Ok(Some(TagType::TAGv12));
+            }
+        }
+
+        // Nope, just v1.0
+        Ok(Some(TagType::TAGv10))
+    } else {
+        Ok(None)
+    }
+}
+
+pub fn remove_tag(file: &mut File, typ: TagType) -> io::Result<()> {
+    let tag_len = match typ {
+        TagType::TAGv10 => 128,
+        TagType::TAGv11 => 128 + 227,
+        TagType::TAGv12 => 128 + 128,
+    };
+
+    let length = file.seek(io::SeekFrom::End(0))?;
+    eprintln!("remove_tag: Resizing file from {} to {} bytes", length, length - tag_len);
+    file.set_len(length - tag_len)?;
+
+    Ok(())
+}
-- 
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